This invention relates to method and apparatus for compression molding of paste to obtain a so-called molded tablet.
In general, the aged have weakened corporal, as well as physiological functions, and often suffer from more or less significant dysphagia which makes it difficult to take a dose of medicine. All the dosage forms commonly used such as a tablet, capsule, granule and powder are often inconvenient for the aged in that a dose of medicine sticks in patient's throat and does not go down the patient's throat due to poor salivation and, particularly in the case of a powder or granule, the patient is readily choked with the powder or granule and the power or granule is apt to be caught by artificial teeth.
In view of such problem, various dosage forms have been developed, which maintain traditional convenience of handling which characterizes a tablet, but which can be easily taken without the necessity of water, even by a patient whose ability to swallow is insufficient.
Such improved dosage forms include the buccal tablet and trochiscus, both of which are suitable for patient having poor swallowing ability. So-called molded tablet also has already been developed, which is usually obtained by filling a mold with a solvent-wetted paste and then drying moldings.
Conventionally, the molded tablet is prepared by a method comprising the steps of wetting a mixture of active ingredients, such as medicine and excipient, with a solvent such as alcohol or water, then rubbing this mixture into a mold, taking off the moldings from the mold and thereafter drying the moldings. This method is known commonly as the rub-in method and executed by using an apparatus well known to the art. This well known method is particularly preferable for preparation of a sublingual tablet or the like requiring rapid dissolution, since the tablet prepared by this method includes no compression step and is relatively soft and disintegration as well as dissolution thereof after the tablet has been taken can be correspondingly accelerated.
However, this well known method is disadvantageously limited in regard to the applicable type of medicine. As to both the buccal tablet and the trochiscus, the type of medicine that is applicable thereto is principally water-soluble and dissolution thereof within patient's mouth inconveniently takes a lot of time.
The type of medicine conventionally applicable to the molded tablet also is water-soluble and preparation of the molded tablet containing fat-soluble medicine has not been reported.
Furthermore, the molded tablet is extremely fragile and its mechanical strength is correspondingly low. Due to a high degree of wear and tear (i.e., degree of damage under a physical shock) and destructibility, the molded tablet of the prior art is inconvenient to handle and the active ingredients in each tablet is liable to become uneven. As to handling, the molded tablet of the prior art has been apt to be damaged during a process of packaging or unpacking.